package Solution;

class Solution {
//125. Valid Palindrome回文字符串
    public boolean  isCharacter(char ch){
        if(ch>='a'&&ch<='z' || ch>='0'&&ch<='9'){
            return true;
        }
        return false;
    }


    public boolean isPalindrome(String s){
        //把所有的字符变成小写
        s=s.toLowerCase();
        int i=0;
        int j=s.length()-1;
        while(i<j){
            while(i<j && !isCharacter(s.charAt(i))){
                i++;
            }
            while(i<j&&!isCharacter(s.charAt(j))){
                j--;
            }
            if(s.charAt(i)!=s.charAt(j)){
                return false;
            }else{
                i++;
                j--;
            }
        }
        return true;
    }

}



